Food flavourings are used in the food industry in a variety of ways. One general type of food flavouring is that which adds grilled or barbeque flavour to foods. Typical grilled flavours include those for the preparation of products wherein the content of meat is reduced or non-existent, for example in sauces, snack foods, meat substitutes, pet foods and the like. Such food flavourings can be sprayed onto the food stuffs, the food can be dipped in a solution of the flavouring, or applied in a variety of different manners. One such composition that provides an aspect of a grill flavour is that disclosed in U.S. Pat. No. 4,571,342 (DiCicca, 1986). This patent describes a flavouring composition with charred flavour notes which is prepared by subjecting a film of fat or oil to temperatures in the range of 150.degree. C. to 475.degree. C. in the presence of oxygen for an effective period of time followed by collecting the fat or oil. The method disclosed in U.S. Pat. No. 4,571,342 involves a continuous flow, thin film apparatus where fat or vegetable oil flows down a tube where a thin film of the fat or vegetable oil is formed around the inside circumference of the tube with a constant flow of air through the centre of the tube. Furthermore, the process is oxidative since heating of the vegetable oil is done in the presence of a substantial amount of oxygen.
A development on the flavouring composition described in U.S. Pat. No. 4,571,342 is disclosed in U.S. Pat. No. 4,820,538 (Schulman, 1989). It is disclosed that when one scales up the DiCicca process, there is an ineffective use of equipment and the reaction is inconsistent. As such, U.S. Pat. No. 4,820,538 teaches use of a rototherm to carry out the reaction in the presence of between 1-11/2 parts of oxygen to 1 part fat or oil. Due to the presence of an equimolar ratio or more of oxygen, this reaction is an oxidative reaction carried out in a thin film heat exchanger. The period of time that the thin film remains in the heat exchanger is for a period of not exceeding 2 minutes and normally in the neighbourhood of 90 seconds. Upon exiting the heat exchanger the combustion products are quenched in less than 20 seconds and commonly in about 10 seconds.
This type of charcoal broil flavouring has achieved some commercial success. However, the product that is obtained utilizing this process has a limited flavour profile and level of flavour concentration. In addition, it is always desirable to have available new and different flavour notes that can be used either directly or in a blended form as a grilled food flavouring.
It has been known that some food flavourings can be made utilizing a fast pyrolysis reactor of the types disclosed in U.S. Pat. Nos. 4,876,108 and 4,994,297 (Underwood, 1989 and 1991, respectively). The food flavouring disclosed in U.S. Pat. No. 4,994,297 comprises liquid smoke, obtained from the pyrolysis of wood or cellulose feed stocks, using the method disclosed in U.S. Pat. No. 4,876,108, to produce a flavouring that is related, but quite distinct from the grilled flavourings described herein. The Underwood composition is made utilizing short residence times and is carried out in an oxygen starved atmosphere. Due to the lack of oxygen, the resulting reactions are reductive, not oxidative. For practical reasons, one never achieves a total absence of oxygen in such a process due to the partial difficulties of voiding all oxygen from a reactor system and therefore it would be understood that an oxygen starved atmosphere would have a limited amount of oxygen, i.e. less than 4% molar ratio of oxygen to feed stock.
The product made in accordance with the disclosure of U.S. Pat. Nos. 4,876,108 and 4,994,297 has also achieved a fair amount of commercial success primarily as a meat flavouring composition having considerable browning characteristics, but does not provide flavour notes that extend beyond those associated with smoked flavours. In U.S. Pat. No. 5,292,541 there is disclosed the production of a food browning material prepared from the pyrolysis of a sugar or starch feed stock. This product, while useful as a browning agent, lacks any appreciable flavouring ability and it is therefore quite distinct from the food flavouring as disclosed herein.